Your question is very good & my answer is: It depends upon the abilities of the human capital to be retained. In some 3rd world countries, you will see retention for persons, who reached the age of retirement, just because they have good connections with the managers or they belong to a certain family or to a particular town. On the other hand, there will be no retention for retiring persons, whatever their expertise is, if these persons are not liked by the managers or they do not have affiliations. Normally, a "good" organization retains "good" employees for some time in order to get the maximum advantage from them & then it says "goodbye" to them. 

Human capital is a conceptual redundancy, and ethically unsavory to boot, and when used in research, one commits a fallacy of misplaced concreteness.

No organisation can perform more than what the people in her employment can contribute....that is the worth of their abilities, skills and knowledge. Therefore, retaining human capital  can be positively associated with organizational performance.

Human capital enhancement can also be viewed in the context of top management

team (TMT). Heterogeneity or sometimes is called diversity in TMT will tend to lead to greater performance because the argument is heterogeneity promotes various characteristics to be absorbed into the workforce team; this includes people of different age groups, functional backgrounds, education backgrounds, tenure and gender.

You can see different impacts depending on what you are looking for, and you have to define what relation you want to analyse. First, I think, you have to select a type of organization to analyse (those with fast increasing profits, or other that are stable for years, not necessarily presenting increasing profits). Maybe you can find companies that retains human capital because they need people to understand their complexity (think about those industries that produces, for example, medical equipments), and so they offer a career in the long run (with low salaries). In this case maybe you can observe low turnover, people that need to feel in safe, etc.

On the other hand, consider retail companies, those that need to have fast responses. These companies may offer high salaries, high level of competition between employees, so turnover tends to be higher that the first one presented in this text. So, for me, the point is what these companies offers in exchange of what is normally done for its employees.

So, the impact of retention of human capital is not isolated from what the company offers (and it has to be clear for everybody), and in my opinion, the company has some power to drive efforts to improve its organizational performance (in my first example, drives through the long run, as they need "time" to development of succesful products); in the second example, drives to deliver results "today"). The point is how to retain human capital highly motivated in a way to achieve desired results, without biases (for example, in the first case, a career in the long run may attract people interested in a place with less probability of loosing their jobs, not exactly people interested in product development, what could bring impact in terms of organizational performance). 

It may help the reader of your question to further operationalize the concepts involved in it (i.e., human capital, impacts, and organizational performance).  For example, retention could be specified as organizational or workforce. 

Thanks all in the web. I request all viewers/followers/researchers in researchgate to provide some meaningful inputs to my given question. 

Thanks.

I agree with Ian on how to address human capital. The recent literature that uses retention of talent, and therefore the hired mental capacity of employees, for the sake to capitalize on human capital and not taking people for granted. Therefore, an organization which respects its human resources and appreciates their contributions to enrich the learning curves, will surely motivate its best people to stay while organizations which do not respect its employees will suffer due to turnover and loss of skills.

Therefore, there is a direct relationship between organizational performance and the accumulated know how from its loyal employees. Consequently, such an organization (an organization with appropriate culture of respect to its people) will seek to retain its talents.

Thank you Hussin Sir.